Crude Oil

Crude oil is a naturally-occurring substance found trapped in certainrocks below the earth?s crust. It is a dark, sticky liquid which,scientifically speaking, is classed as a hydrocarbon. This means, itis a compound containing only hydrogen and carbon. Crude oil is highlyflammable and can be burned to create energy. Along with its sisterhydrocarbon, natural gas, crude oil makes an excellent fuel.Hydrocarbons are organic molecules that contain only carbon ? and hydrogen (H). Examples of hydrocarbons: n Methane n Propane n Benzene n Etcâ??â?? Unsaturated & Saturated Hydrocarbons 1. Saturated Hydrocarbons Saturated hydrocarbons contain only single carbon-carbon bonds, and therefore contain the greatest possible number of hydrogen atoms for their number of carbon atoms. E.g. Â? Alkanes Â? Branched Alkanes 2. Unsaturated Hydrocarbons Unsaturated hydrocarbons contain double and triple carbon-carbon bonds, and therefore do not contain the greatest possible number of hydrogen atoms for their number of carbon atoms. E.g. Â? Benzene Â? Alkenes Â? Alkynes Source: http://www.vincentmassey.ca If there is not enough oxygen present to completely burn the fuel to carbon dioxide and water other products may form. The most common partially burned products are likely to be carbon C (soot) and deadly carbon monoxide CO. It would appear that the hydrogen in the fuel molecules is more easily burned and usually forms water. eg ch4 + o2 => C(s) + 2H2O(l) or 2CH4(g) + 3O2(g) => 2CO(g) + 4H2O(l) Therefore it is extremely important that any combustion system is as efficient as possible eg gas heaters, furnaces etc must all have excellent ventilation for complete combustion to harmless water and carbon dioxide. Carbon monoxide is colourless and odourless and even low concentrations in the air can be fatal. Carbon monoxide is unfortunately emitted by all car exhausts, though catalytic converters help reduce this by converting nitrogen monoxide (another pollutant) and carbon monoxide into harmless nitrogen and carbon dioxide. 2NO(g) + 2CO(g) => n2 + 2CO2(l) source: http://www.wpbschoolhouse.btinternet.co.uk/ The Problem of Incomplete Combustion ======== Fossil fuels are a complex mixture of carbon and hydrogen-containing molecules referred to as hydrocarbons (HC). In addition to the pure hydrocarbon molecules, fuels also have a small fraction of molecules containing nitrogen, sulphur and other elements including many metals such as vanadium. Poor quality fuels, such as coals, are comprised of very large, mostly carbon containing molecules. The amount of hydrogen in the fuel increases as the size of the molecules decrease and the quality of the fuel increases. Higher quality fuels which have more hydrogen and smaller molecules burn faster and more completely. When fossil fuels burn, oxygen is reacting with the hydrocarbon molecules to produce carbon dioxide (CO2), water (H2O), oxides of the trace elements (Nox, Sox, Vox, etc. where x is 0 or a small number) and heat. How completely the hydrocarbons burn depends upon three basic factors: Â? The rate at which the molecules burn. (This rate is a function of how large the molecules are.) Â? How much oxygen is present around the fuel molecules Â? The length of time that the fuel molecules spend in the fireball Some of the harmful waste products and effects are: Â? Black Smoke problems. Â? Slagging, fouling, and corrosion of the car. Carbon particles (soot), and condensed tar, result from the incomplete combustion of fuels. When present in sufficient particle size and quantity, soot in exhaust gases constitutes a black smoke. Although soot is not the most abundant pollutant, it may be one of the most hazardous since soot particles are the proper size to be ingested deep into the lungs. In addition, the polycyclic aromatic hydrocarbons (PAH?s) which are absorbed on soot can promote skin cancer in humans, as many PAH?s are known to be carcinogenic. (A cancer-causing substance or agent.) Research also indicates that soot adsorbs sulphuric acid formed during combustion and contributes to its formation via reactions on the carbon surface. The adsorbed H2SO4 can be as much as 20% by weight of the carbon retained in the boiler. If allowed to escape into the atmosphere, it can cause acid smut fallout and boiler cold-temperature corrosion. What is a catalytic converter and how does it work? =========== A catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds. The three harmful compounds are: Â? Hydrocarbons (in the form of unburned gasoline) Â? Carbon monoxide (formed by the combustion of gasoline) Â? Nitrogen oxides (created when the heat in the engine forces nitrogen in the air to combine with oxygen) Carbon monoxide is a poison for any air-breathing animal. Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog. In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen. I have heard that carbon monoxide is extremely poisonous. Can you explain why? Every poison has a particular trait that causes it to be poisonous. In the case of carbon monoxide, the trait has to do with haemoglobin in the blood. Haemoglobin is made up of complex proteins that bind to iron atoms. The structure of the protein and its iron atom causes oxygen to bind to the iron atom very loosely. When blood passes through the lungs, the iron atoms in the haemoglobin bind to oxygen atoms. When the blood flows into areas of the body that are lacking in oxygen, the iron atoms release their oxygen. The difference in oxygen pressure in the lungs and in the parts of the body needing oxygen is very slight. The haemoglobin is very finely tuned to absorb and release oxygen at just the right times. Carbon monoxide, on the other hand, binds very strongly to the iron in haemoglobin. Once carbon monoxide attaches, it is very difficult to release. So if you breathe in carbon monoxide, it sticks to your haemoglobin and takes up all of the oxygen binding sites. Eventually, your blood loses all of its ability to transport oxygen, and you suffocate. Because carbon monoxide binds to haemoglobin so strongly, you can be poisoned by carbon monoxide even at very low concentrations if you are exposed for a long period of time. Concentrations as low as 20 or 30 parts per million (ppm) can be harmful if you are exposed for several hours. Exposure at 2,000 ppm for one hour will cause unconsciousness. Many common devices produce carbon monoxide, including cars, gas appliances, wood stoves and cigarettes. Solutions to Air Pollution A catalytic converter is a pollution-control device placed in the exhaust system of an automobile. It was in the 1980?s that the United States passed a federal law that required all new automobiles to have catalytic converters. A catalytic converter takes the carbon monoxide and hydrocarbons that are given off as waste from the combustion of gasoline in the car?s engine and converts them into water and carbon dioxide gas. Since water and carbon dioxide cycle through the environment they are safer than carbon monoxide and hydrocarbons, the converters also convert nitrous oxides into nitrogen gas, which naturally makes up 78% of air. A catalytic converter is coated with platinum and rhodium (both catalysts), all spread out over a honey comb structure for a greater surface area. The exhaust gases pass through the converter where the catalysts speed up the oxidation reactions to turn the harmful gases into less harmful substances. Sources:>>>>>>>>>>>>>>>>>>AGAINST<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< C(s) + 2H2O(l) Or 2CH4(g) + 3O2(g) => 2CO(g) + 4H2O(l)